Analysis of the evolution of influenza-immune effector T cells in thymus, lymph node and spleen of both baby mice, and irradiated adult mice reconstituted with syngeneic bone marrow. The application of the limit dilution protocol to studying the evolution of the T cell response, and the effect of age, intercurrent infection and graft-versus-host disease on the survival of memory T cells. Use of the limit dilution protocol to further examine the frequency of influenza-specific T cells in immunologically naive mice. The effect of helper factors and radiation-resistant T cell help will be assessed in this system. Development of clones of influenza-specific cytotoxic T cells for the analysis of fine specificity patterns of T cell recognition.